The difference boolean doesn't seem to work on a specific area
The Boolean modifier relies on correctly set normals. Check if your normals are all facing outwards by checking &quot;Face Orientation&quot; in the Viewport Overlays menu:

All the outward faces should be blue. If an object has incorrect normals, you can select all of its faces (A) in edit mode, and Mesh &gt; Normals &gt; Recalculate Outside (ShiftN)